This invention relates generally to an automatic tool changer for a machine tool and, more particularly, to programmable apparatus for automatically changing the punch, stripper and die of a punch press.
The tool changing apparatus of the present invention is especially useful in connection with a punch press of the type in which the punch, stripper and die are held removably in a cartridge when the tools are idle. When the tools are to be used, the cartridge is inserted into the press, the tool holding devices of the press are actuated to lock the tools in the press, and then the cartridge is withdrawn to leave the tools in the press. When the tools have completed their work, the cartridge is returned to pick up the tools preparatory to another cartridge with different tools being inserted into the press.
In the machine tool organization of the invention, several cartridges (e.g., eighty cartridges) all with different tools are contained in a tool storage rack having vertically spaced shelves for holding the cartridges. The automatic tool changing apparatus includes a transfer mechanism or so-called "robot" which is shifted to a selected tool cartridge on a storage shelf, lifts the cartridge from the shelf, shifts the cartridge horizontally toward the punch press, inserts the cartridge into the press to deliver the tools to the press and then withdraws from the press while the tools are being used. After the tools have completed their punching operation, the transfer mechanism re-inserts the cartridge into the press to pick up the tools, shifts the cartridge back to the storage rack, lowers the cartridge onto the shelf and releases the cartridge preparatory to shifting to a different position to pick up another cartridge at a different location on the rack.
When a tool changing transfer mechanism is in the form of a true robot, it is a difficult and very time-consuming operation to program or "teach" the robot to shift to all of its various positions and to stop at precisely predetermined locations. Such "teaching" is conventionally accomplished by a person leading the robot step-by-step through its various moves and positions and using a teaching control to establish the program as the robot is placed through its moves. This usually must be done after the machine tool and the tool changer have been installed and, in most cases, the robot of each tool changer of a like group must be separately and individually programmed.